Open top receptacles, such as open bed trailers, railroad cars, or other containers, either mobile or stationary, frequently must be covered, such as when loaded with loose material. The cover prevents the material within the container from being blown from the container either by the wind or by the flow of air induced when the container moves. Also, many materials, such as sand or grain, must be protected from the elements, and a cover provides such protection. Further, materials such as cement or refuse must be maintained within the confines of the receptacle to protect the environment.
Large open top receptacles are constructed with an open top for easy top loading. The requirements of a cover are fulfilled by providing a flexible removable cover, such as one made of canvas, which is secured over the top of the open top receptacle once the material to be contained has been loaded. Although a simple fabric sheet may be used as a cover, the problems of handling such a large piece of fabric material and of storing the cover when it is not positioned over the open top receptacle makes such a solution less than optimal. Covers that are stored on a roll and are extended over the opening of the receptacle are an improvement over a simple fabric sheet, but fail to adequately cover the opening near the edges of the receptacle, allowing material to escape.
Commonly, a receptacle cover of a truck will add significant height to the truck because the roll that stores the cover resides over the major plane of the cover. The added height can result in a serious vertical clearance problem whenever the truck attempts to travel under an overpass with a height less than the combined heights of the truck and the roll. It is also known for the mechanism used to move a receptacle cover over the opening of the receptacle to be wider than the receptacle itself, thereby creating the possibility for a horizontal clearance problem.